Various technologies exist for the delivery of voice communication over a network. Telephone devices may communicate via the public switched telephone network (PSTN), which is a circuit-switched network that includes telephone lines, fiber-optic cables, microwave transmission links, and other types of links interconnected via switching centers. Voice communication may also be implemented in a packed-switched Internet Protocol (IP) network through the use of Voice over IP (VoIP) technologies. VoIP may be implemented using Session Initiation Protocol (SIP). A private SIP network may be used by an enterprise as an inexpensive solution to connect multiple locations for telephone service.